<a href="http://github.com/angular/angular.js/tree/v1.2.8/src/auto/injector.js#L100" class="view-source btn btn-action"><i class="icon-zoom-in"> </i> View source</a><a href="http://github.com/angular/angular.js/edit/master/src/auto/injector.js" class="improve-docs btn btn-primary"><i class="icon-edit"> </i> Improve this doc</a><h1><code ng:non-bindable="">$injector</code>
<div><span class="hint">service in module <code ng:non-bindable="">AUTO</code>
</span>
</div>
</h1>
<div><h2 id="description">Description</h2>
<div class="description"><div class="auto-injector-page"><p><code>$injector</code> is used to retrieve object instances as defined by
<a href="api/AUTO.$provide"><code>provider</code></a>, instantiate types, invoke methods,
and load modules.</p>
<p>The following always holds true:</p>
<pre class="prettyprint linenums">
  var $injector = angular.injector();
  expect($injector.get('$injector')).toBe($injector);
  expect($injector.invoke(function($injector){
    return $injector;
  }).toBe($injector);
</pre>
<h3 id="description_injection-function-annotation">Injection Function Annotation</h3>
<p>JavaScript does not have annotations, and annotations are needed for dependency injection. The
following are all valid ways of annotating function with injection arguments and are equivalent.</p>
<pre class="prettyprint linenums">
  // inferred (only works if code not minified/obfuscated)
  $injector.invoke(function(serviceA){});

  // annotated
  function explicit(serviceA) {};
  explicit.$inject = ['serviceA'];
  $injector.invoke(explicit);

  // inline
  $injector.invoke(['serviceA', function(serviceA){}]);
</pre>
<h4 id="description_injection-function-annotation_inference">Inference</h4>
<p>In JavaScript calling <code>toString()</code> on a function returns the function definition. The definition
can then be parsed and the function arguments can be extracted. <em>NOTE:</em> This does not work with
minification, and obfuscation tools since these tools change the argument names.</p>
<h4 id="description_injection-function-annotation_-annotation"><code>$inject</code> Annotation</h4>
<p>By adding a <code>$inject</code> property onto a function the injection parameters can be specified.</p>
<h4 id="description_injection-function-annotation_inline">Inline</h4>
<p>As an array of injection names, where the last item in the array is the function to call.</p>
</div></div>
<div class="member method"><h2 id="methods">Methods</h2>
<ul class="methods"><li><h3 id="methods_annotate">annotate(fn)</h3>
<div class="annotate"><div class="auto-injector-annotate-page"><p>Returns an array of service names which the function is requesting for injection. This API is
used by the injector to determine which services need to be injected into the function when the
function is invoked. There are three ways in which the function can be annotated with the needed
dependencies.</p>
<h4 id="methods_annotate_argument-names">Argument names</h4>
<p>The simplest form is to extract the dependencies from the arguments of the function. This is done
by converting the function into a string using <code>toString()</code> method and extracting the argument
names.
<pre class="prettyprint linenums">
  // Given
  function MyController($scope, $route) {
    // ...
  }

  // Then
  expect(injector.annotate(MyController)).toEqual(['$scope', '$route']);
</pre>
<p>This method does not work with code minification / obfuscation. For this reason the following
annotation strategies are supported.</p>
<h4 id="methods_annotate_the-property">The <code>$inject</code> property</h4>
<p>If a function has an <code>$inject</code> property and its value is an array of strings, then the strings
represent names of services to be injected into the function.
<pre class="prettyprint linenums">
  // Given
  var MyController = function(obfuscatedScope, obfuscatedRoute) {
    // ...
  }
  // Define function dependencies
  MyController['$inject'] = ['$scope', '$route'];

  // Then
  expect(injector.annotate(MyController)).toEqual(['$scope', '$route']);
</pre>
<h4 id="methods_annotate_the-array-notation">The array notation</h4>
<p>It is often desirable to inline Injected functions and that&#39;s when setting the <code>$inject</code> property
is very inconvenient. In these situations using the array notation to specify the dependencies in
a way that survives minification is a better choice:</p>
<pre class="prettyprint linenums">
  // We wish to write this (not minification / obfuscation safe)
  injector.invoke(function($compile, $rootScope) {
    // ...
  });

  // We are forced to write break inlining
  var tmpFn = function(obfuscatedCompile, obfuscatedRootScope) {
    // ...
  };
  tmpFn.$inject = ['$compile', '$rootScope'];
  injector.invoke(tmpFn);

  // To better support inline function the inline annotation is supported
  injector.invoke(['$compile', '$rootScope', function(obfCompile, obfRootScope) {
    // ...
  }]);

  // Therefore
  expect(injector.annotate(
     ['$compile', '$rootScope', function(obfus_$compile, obfus_$rootScope) {}])
   ).toEqual(['$compile', '$rootScope']);
</pre>
</div><h5 id="methods_annotate_the-array-notation_parameters">Parameters</h5><table class="variables-matrix table table-bordered table-striped"><thead><tr><th>Param</th><th>Type</th><th>Details</th></tr></thead><tbody><tr><td>fn</td><td><a href="" class="label type-hint type-hint-function">function</a><a href="" class="label type-hint type-hint-array">Array.&lt;string|Function&gt;</a></td><td><div class="auto-injector-annotate-page"><p>Function for which dependent service names need to
be retrieved as described above.</p>
</div></td></tr></tbody></table><h5 id="methods_annotate_the-array-notation_returns">Returns</h5><table class="variables-matrix"><tr><td><a href="" class="label type-hint type-hint-array">Array.&lt;string&gt;</a></td><td><div class="auto-injector-annotate-page"><p>The names of the services which the function requires.</p>
</div></td></tr></table></div>
</li>
<li><h3 id="methods_get">get(name)</h3>
<div class="get"><div class="auto-injector-get-page"><p>Return an instance of the service.</p>
</div><h5 id="methods_get_parameters">Parameters</h5><table class="variables-matrix table table-bordered table-striped"><thead><tr><th>Param</th><th>Type</th><th>Details</th></tr></thead><tbody><tr><td>name</td><td><a href="" class="label type-hint type-hint-string">string</a></td><td><div class="auto-injector-get-page"><p>The name of the instance to retrieve.</p>
</div></td></tr></tbody></table><h5 id="methods_get_returns">Returns</h5><table class="variables-matrix"><tr><td><a href="" class="label type-hint type-hint-object">*</a></td><td><div class="auto-injector-get-page"><p>The instance.</p>
</div></td></tr></table></div>
</li>
<li><h3 id="methods_has">has(Name)</h3>
<div class="has"><div class="auto-injector-has-page"><p>Allows the user to query if the particular service exist.</p>
</div><h5 id="methods_has_parameters">Parameters</h5><table class="variables-matrix table table-bordered table-striped"><thead><tr><th>Param</th><th>Type</th><th>Details</th></tr></thead><tbody><tr><td>Name</td><td><a href="" class="label type-hint type-hint-string">string</a></td><td><div class="auto-injector-has-page"><p>of the service to query.</p>
</div></td></tr></tbody></table><h5 id="methods_has_returns">Returns</h5><table class="variables-matrix"><tr><td><a href="" class="label type-hint type-hint-boolean">boolean</a></td><td><div class="auto-injector-has-page"><p>returns true if injector has given service.</p>
</div></td></tr></table></div>
</li>
<li><h3 id="methods_instantiate">instantiate(Type, locals)</h3>
<div class="instantiate"><div class="auto-injector-instantiate-page"><p>Create a new instance of JS type. The method takes a constructor function invokes the new
operator and supplies all of the arguments to the constructor function as specified by the
constructor annotation.</p>
</div><h5 id="methods_instantiate_parameters">Parameters</h5><table class="variables-matrix table table-bordered table-striped"><thead><tr><th>Param</th><th>Type</th><th>Details</th></tr></thead><tbody><tr><td>Type</td><td><a href="" class="label type-hint type-hint-function">function</a></td><td><div class="auto-injector-instantiate-page"><p>Annotated constructor function.</p>
</div></td></tr><tr><td>locals <div><em>(optional)</em></div></td><td><a href="" class="label type-hint type-hint-object">Object</a></td><td><div class="auto-injector-instantiate-page"><p>Optional object. If preset then any argument names are read from this
object first, before the <code>$injector</code> is consulted.</p>
</div></td></tr></tbody></table><h5 id="methods_instantiate_returns">Returns</h5><table class="variables-matrix"><tr><td><a href="" class="label type-hint type-hint-object">Object</a></td><td><div class="auto-injector-instantiate-page"><p>new instance of <code>Type</code>.</p>
</div></td></tr></table></div>
</li>
<li><h3 id="methods_invoke">invoke(fn, self, locals)</h3>
<div class="invoke"><div class="auto-injector-invoke-page"><p>Invoke the method and supply the method arguments from the <code>$injector</code>.</p>
</div><h5 id="methods_invoke_parameters">Parameters</h5><table class="variables-matrix table table-bordered table-striped"><thead><tr><th>Param</th><th>Type</th><th>Details</th></tr></thead><tbody><tr><td>fn</td><td><a href="" class="label type-hint type-hint-object">!function</a></td><td><div class="auto-injector-invoke-page"><p>The function to invoke. Function parameters are injected according to the
<a href="guide/di">$inject Annotation</a> rules.</p>
</div></td></tr><tr><td>self <div><em>(optional)</em></div></td><td><a href="" class="label type-hint type-hint-object">Object</a></td><td><div class="auto-injector-invoke-page"><p>The <code>this</code> for the invoked method.</p>
</div></td></tr><tr><td>locals <div><em>(optional)</em></div></td><td><a href="" class="label type-hint type-hint-object">Object</a></td><td><div class="auto-injector-invoke-page"><p>Optional object. If preset then any argument names are read from this
object first, before the <code>$injector</code> is consulted.</p>
</div></td></tr></tbody></table><h5 id="methods_invoke_returns">Returns</h5><table class="variables-matrix"><tr><td><a href="" class="label type-hint type-hint-object">*</a></td><td><div class="auto-injector-invoke-page"><p>the value returned by the invoked <code>fn</code> function.</p>
</div></td></tr></table></div>
</li>
</ul>
</div>
</div>
